3342 2012-10-26 22:45:43 +0000 perf script: improve 'live mode' 2017-06-13 11:12:57 +0000 1 1 7 Build System, Metadata & Runtime OE-Core kernel 1.4 x86 Multiple RESOLVED INVALID Low enhancement Future 1 tom.zanussi tom.zanussi bruce.ashfield dvhart joshuagloe tom.zanussi --- --- Don't know oldest_to_newest 26984 0 tom.zanussi 2012-10-26 22:45:43 +0000 The 'live mode' in perf script essentially sends the stdout of the record process to the stdin of the report process through a pipe. This is OK for low-volume events e.g. for 'perf script rwtop', but breaks down at high volume: root@crownbay:~# perf script sctop syscall events: event count ---------------------------------------- ---------- 3 88768 240 1208 4 127 54 51 265 18 168 18 102 18 142 14 192 12 104 12 91 12 78 12 13 10 146 6 43 4 195 2 197 1 ^CWarning: Processed 589913 events and lost 179 chunks! Check IO/CPU overload! There also seems to be some kind of drawing problem with the display for this script as you can see it visibly drawing line by line. 28959 1 tom.zanussi 2013-01-18 20:49:35 +0000 As a start to this, I've sent out a patchset to lkml that fixes various related problems: http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg370505.html In a lot of cases the high loads are a result of tracing perf-related activity, so I also experimented with the event filters to screen out perf-originated events. e.g. to screen out perf write events: [root@empanada ~]# export x=`expr \`ls /proc/self/task\` + 1`;perf record -a -e syscalls:sys_enter_read -e syscalls:sys_exit_read -e syscalls:sys_enter_write --filter "common_pid != $x" -e syscalls:sys_exit_write --filter "common_pid != $x This works but is pretty unwieldy - need to try to come up with an easier interface that still uses the kernel event filtering engine. 74061 2 joshuagloe 2017-06-13 11:12:57 +0000 This bug is tracking an enhancement to perf which does not fall under the YP umbrella.